DIY: Friction Welding Warped 3D Prints

July 14, 2017 ProgressTH 3D printing is a great way to create prototypes, do small batch production, and customized one-off solutions. Having a wide variety of post-print techniques can help you create designs many times larger than your printer's print space, and combine parts in ways they couldn't simply be printed out as.

During the design and construction of these custom 14.5 liter (3.8 gallon) aquaponic systems, a large platform and cover was printed out. The parts were too big to print whole, so the bottom platform, the sides of the case, and the cover were all printed in halves.

The platform and top cover were easily connected through a process known as friction welding (described in detail in this Hackaday link). A rotary tool with a short length of 3D printing filament inserted instead of a drill bit is spun where two pieces are to be welded together. The friction from the spinning filament fuses the plastic together and a bead can be formed from one side of the weld to the other.

Click image to enlarge. Note the gap  in #2 and the difference between #2 and #3 before and after the filament is inserted. #4 shows the finished seam. 
However, the sides of the case were tall prints and had some warping due to the shape and the difference in temperatures as parts of the print cooled as others were hot.

Filling the large gap where the two halves meet up is relatively simple. Looking at the series of images above:
  1. The two halves are lined up;
  2. Spot welds are done where they lined up closest (at the top and bottom);
  3. A length of filament is inserted into the gap;
  4. Welding the filament into place and then welding over the gap gives a finished seam. 
So the next time you have a similar project and end up with slightly warped piece and resulting gaps that glue or a quick friction weld can't handle, try this technique to bridge the gap.